The signal to noise ratio of a weak FM stereo signal is much worse than that of an equally weak mono signal. It has been found that to achieve an acceptable signal to noise ratio the stereo signal must be about 20 db stronger than a mono signal. In the stereo receiver the L-R channel can be attenuated with respect to the L+R channel to achieve the noise advantages of mono performance. Of course, this is achieved with a loss of stereo separation. In a typical example, if the signal is above about 30 microvolts the L-R channel is operated at full level and the stereo reception is capable of greater than 50 db separation. At 3 microvolts input the L-R channel is attenuated 20 db to produce essentially mono operation. This is called blend. In the range between 3 and 30 microvolts, the L-R channel attenuation is inversely proportional to signal strength. This form of control has produced the most acceptable stereo system performance. In order to achieve a signal related blend the L-R channel attenuation must be responsive to a control voltage input. The LM1870 is a Stereo Demodulator with Blend and is available from National Semiconductor Corporation. The LINEAR DATABOOK .COPYRGT. 1982 lists the IC characteristics and an operating supply voltage of 7-15 volts is specified. The safe DATABOOK lists the LM4500A which is a High Fidelity FM Stereo Demodulator with Blend and is also available from National Semiconuctor Corporation. Its supply range is listed at 8-16 volts. Both of these devices are useful in automobile and high performance portable radios. However, they do not operate at the low voltages normally desired in battery operated radios.